that the action on the case adopts the severe rule just suggested for trespass, except when the action is founded on a contract.  Negligence, it might be said, had nothing to do with the common-law liability for a nuisance, and it might be added that, where negligence was a ground of liability, a special duty had to be founded in the defendant’s super se assumpsit, or public calling. 1 On the other hand, we shall see what can be said for the proposition, that even in trespass there must at least be negligence.  But whichever argument prevails for the one form of action must prevail for the other.  The discussion may therefore be shortened on its technical side, by confining it to trespass so far as may be practicable without excluding light to be got from other parts of the law.

As has just been hinted, there are two theories of the common-law liability for unintentional harm.  Both of them seem to receive the implied assent of popular textbooks, and neither of them is wanting in plausibility and the semblance of authority.

The first is that of Austin, which is essentially the theory of a criminalist.  According to him, the characteristic [82] feature of law, properly so called, is a sanction or detriment threatened and imposed by the sovereign for disobedience to the sovereign’s commands.  As the greater part of the law only makes a man civilly answerable for breaking it, Austin is compelled to regard the liability to an action as a sanction, or, in other words, as a penalty for disobedience.  It follows from this, according to the prevailing views of penal law, that such liability ought only to be based upon personal fault; and Austin accepts that conclusion, with its corollaries, one of which is that negligence means a state of the party’s mind. 1 These doctrines will be referred to later, so far as necessary.

The other theory is directly opposed to the foregoing.  It seems to be adopted by some of the greatest common law authorities, and requires serious discussion before it can be set aside in favor of any third opinion which may be maintained.  According to this view, broadly stated, under the common law a man acts at his peril.  It may be held as a sort of set-off, that he is never liable for omissions except in consequence of some duty voluntarily undertaken.  But the whole and sufficient ground for such liabilities as he does incur outside the last class is supposed to be that he has voluntarily acted, and that damage has ensued.  If the act was voluntary, it is totally immaterial that the detriment which followed from it was neither intended nor due to the negligence of the actor.

In order to do justice to this way of looking at the subject, we must remember that the abolition of the common-law forms of pleading has not changed the rules of substantive law.  Hence, although pleaders now generally [83] allege intent or negligence, anything which would formerly have been sufficient to charge a defendant in trespass is still sufficient, notwithstanding the fact that the ancient form of action and declaration has disappeared.